The Garrison book has a good set of spacing for rods in the appendix.

A Master's Guide to Building a Bamboo Fly Rod by Everett Garrison, Hoagy B. Carmichael

Else, you can tape on guides and string up the rod and get it under tension so it bends. Look for flat spots on the line and adjust the guides to match the rod. Really, that is an excellent way to match the taper of the rod (how and where it bends) to the placement of the guides.

Scott T